Federal regulators are suing T-Mobile for knowingly adding charges its customers never authorized. Those charges were for things like horoscope texts or pricey ringtones.

The Federal Trade Commission says these bogus charges were crammed into user’s bills from 2009 through last December. And it says T-Mobile got a 35 to 40 percent cut, amounting to hundreds of millions of dollars.

T-Mobile is dismissing the lawsuit, calling it unfounded and sensational, but the government says the company got away with this for four years because of long, confusing bills. That made these charges hard to detect.

And if a judge sides with regulators, you can bet refunds aren’t out of the realm of possibility.

This suit comes as T-Mobile, the country’s third largest carrier, tries to paint itself as something different. It’s had an aggressive marketing campaign, saying it’s doing away with contracts, dropping international roaming, and paying customers $650 to switch from other carriers.

It’s also reportedly seeking approval for a $32 billion merger with Sprint.